Directing sail

ABSTRACT

This invention is directed to provide a novel sail arrangement comprising a main sail not secured to a central mast, and provided with means permitting the setting of this main sail in three directions, i.e., longitudinally, laterally and angularly in a horizontal plane. With these three specific adjustments, the coxswain can take due account of all the reactions produced by the sail on the vessel and control the head, the list, the nosediving, or bow drop, and the speed of the vessel with a high degree of precision and without resorting to a rudder.

United States Patent [191 Lenoble 1 Jan. 7, 1975 DIRECTING SAIL [76] Inventor: Jean-Paul Lenoble, 94, rue Broca,

Paris, France 75013 22 Filed: Feb.2l, 1973 211 App]. No; 334,436

[30] Foreign Application Priority Data Feb. 22, 1972 France 72.05912 [52] U.S. Cl. ll4/l03, 114/39 [51] Int. Cl B6311 9/06 [58] FieldofSearch...ll4/l02,103,39,43,235WS; 9/310 R, 310 D, 310 E; 280/1l.37 S

[56] References Cited UNITED STATES PATENTS 302,517 7/1884 Nelson 280/1137 S 1,859,178 5/1932 Sprinkle.... 2,577,917 12/1951 Root 2,793,870 5/1957 Bowman 114/103 3,455,261 7/1969 Perrin 9/310 E Primary Examiner-Trygve M. Blix Assistant Examiner-Stuart M. Goldstein Attorney, Agent, or Firm-Davis, Hoxie, Faithful] & Hapgood [57] ABSTRACT This invention is directed to provide a novel sail arrangement comprising a main sail not secured to a central mast, and provided with means permitting the setting of this main sail in three directions, i.e., longitudinally, laterally and angularly in a horizontal plane. With these three specific adjustments, the coxswain can take due account of all the reactions produced by the sail on the vessel and control the head, the list, the nose-diving, or bow drop, and the speed of the vessel with a high degree of precision and without resorting to a rudder.

7 Claims, 7 Drawing Figures Patented Jan. 7, 1975 3,858,542

2 Sheets-Sheet 1 Patented Jan. 7, 1975 2 Sheets-Sheet 2 DIRECTING SAIL The present invention relates in general to sails and has specific reference to a directing sail adapted to propel a vehicle by utilizing the natural energy of wind. It is applicable in general to all vehicles, but more particularly to those travelling on water, especially sailboats and water-skiing gears.

This invention is directed to provide a novel type of sail which is more efficient, in that it improves the speed, stability and manoeuvrability of sail boats.

Since time immemorial, sail boats are equipped with one or a plurality of masts disposed along the longitudinal center line of the boat. These masts are attended by two characteristic and main reactions:

since the sailboat is constantly in a state of equilibrium with respect to the wind force, the coxswain must constantly limit the list of the vessel by reducing the sail angle in relation to the wind direction;

conventional sail riggings react on the boat by changing its direction. By construction or as a consequence of adjustments, ships are referred to as griping or slab, according to their tendency to beat up to windward, or on the contrary to fall off. To compensate this reaction, the coxswain must correct the course by actuating the rudder, but this obviously increases the drag.

Consequently, this invention is directed to provide a novel sail arrangement comprising a main sail not secured to a central mast, and provided with means permitting the setting of this main sail in three directions, i.e., longitudinally, laterally, and angularly in a horizontal plane. With these three specific adjustments, the coxswain can take due account of all the reactions produced by the sail on the vessel and control the head, the list, the nose-diving or bow drop, and the speed of the vessel with a high degree of precision and without resorting to a rudder.

According to a typical form of embodiment of this invention, designed for propelling a water skier, this sail is characterized in that it is stretched by means of at least two spars kept in proper space relationship by a cross spar so positioned that the center of gravity of the assembly comprising the sail and said spars lies centrally of said cross spar, and the thrust center of the sail is merged into, or located behind, this center of gravity, and that it comprises sheets of adjustable length, each leading to one of the apices of the sail by converging to a point held in one of the skiers hands, the other hand of the skier holding the sail by the middle point of the aforesaid spar. Thus, the user can keep the sail at the proper and desired angle for heading to the selected point of his travel.

Reference will now be made to the attached drawings for describing more in detail a few typical forms of embodiment of this invention. In the drawings:

FIGS. 1 to 4 inclusive are diagrams illustrating the basic principle of operation of the sail according to this invention; and,

FIGS. 5 to 7 inclusive illustrate a typical application of the sail system of this invention to a water ski or skid.

Reference will firstly be made to FIGS. 1 to 4 in order to clearly illustrate the mode of operation of the device of this invention. The sail system described hereinafter is based entirely on the control of angular relationships or simply angles. In a later part of this specification, the possibility of adopting a sail control system based on cartesian coordinates will be explained.

In the diagram of FIG. 1, the straight line A0 designates the fictitious mast, and XX is the longitudinal axis of the vessel, the latter travelling in the direction of the arrow F. The sail is shown in the form of a triangle ABB, of which the median line AM gives the wind thrust center CP. The fictitious mast A0 is aligned with the drift center CD and the center of gravity G of the vessel, and therefore constitutes the vertical axis of the boat. The plane AOM is a vertical plane containing both the thrust center CP and the fictitious mast A0 about which it can rotate when the sail is moved.

When the sail is perpendicular to the plane AOM, the resultant force F of the wind VT, which is normal to the sail at CP, lies in the plane AOM and therefore intersects the axis AO. In this position, no head torque is developed, and the sail is neutral. If no other force interferes, the vessel will keep a constant head.

Under these conditions, the following angles can be controlled by the coxswain:

l. The angle a formed between the above defined plane AOM and the longitudinal axis or center line XX of the boat. With this adjustment, it is possible to obtain the optimum thrust force FF and drift force FD while developing the highest possible propelling force FI-I. Its function is, therefore, the same as that resulting from the adjustment of the angle formed between the boom of a conventional sail structure and the boat axis (FIG. 2).

The force FH is the horizontal resultant of the force F exerted normally to the sail at the thrust center CP (see FIG. 3).

The highest thrust force FF is obtained when a M2 while disregarding the secondary forces exerted by the wind on the hull and the rigging, i.e., the top-hamper. The force FF is the drag of the sail proper.

Under certain navigational circumstances, it is advisable to choose a setting giving a slightly lower thrust force FP in order to obtain a substantially lower drift force FD, as those skilled in the art will readily infer from FIG. 2;

2. the angle B, which is the vertical angle formed between the sail and the fictitious mast A0 in the plane AOM. It is the proper adjustment of this angle that stabilizes the vessel by reducing or zeroing the list and the dwnward movement of the bow. Theoretically, and as illustrated in FIG. 3, to reduce these two values completely, the extension of the resulting wind force F must necessarily pass through the center of gravity G. Under these conditions, the angle 5 would be fixed, since the function of the ships structure (cos B ACP/AG is independent of the wind force. However, the efficiency would remain rather low, for an abnormally large fraction of the wind force would be utilized for lifting the vessel instead of propelling same forwards. Therefore, as usual, a compromise must be achieved and the possibility of adjusting the angle B must be preserved, inasmuch as the hull of the boat, and more particularly that of catamarans, provides by construction a resistance to list and bow-drop which will reduce these list and bowdrop effects to practically negligible values, with a reasonable angle B. Theory proves that the smaller the angle [3 and the stronger the wind, the higher the list torque.

The angle [3 will be adjusted as a function of the wind force. With weak wind, it may be zero. Increasing wind forces will lead to a maximum value of B beyond which it will be advisable to shorten the sail.

As in FIG. 2, the force FF is the sail drag or its hamper in a vertical plane. The force F is the normal to the sail, and force FS is a lifting force which, by lightening the vessel will permit of obtaining a hovering effect much more rapidly than with conventional boats.

The force FH is the horizontal resultant really usable for propelling the vessel, as shown in FIG. 2;

3. the angle 7 formed by the boom with respect to the perpendicular to the plane AOM. The adjustment of this angle 7 permits of changing the head or maintaining a predetermined head by oscillating about a position of equilibrium. As shown in FIG. 4, a head torque CC FH X A0.C is obtained, which is applied to the axis of rotation A of the vessel and tends to tack the latter in the direction of the arrow, i.e., a-port.

When the tacking manoeuvre is completed, it is obvious that given the new wind angle A, a new angle a must be adjusted, and a neutral position with a zero angle 7 will have to be found.

In case of prolonged tacking of the vessel, for example along a half-circular path, an angle 'y must be selected which will determine somewhat the radius of rotation and the angle a will be varied constantly and continuously in order to obtain the optimum values of forces FF and FD.

Although it provides different results, the adjustment of said angle 7 is somewhat similar to the adjustment of a conventional main sail, and will be accomplished, in this exemplary form of embodiment, by utilizing a sheet.

The sail system of which the basic principle has been explained in the foregoing, may for instance be applied to the propelling of a water skier, as illustrated in FIGS. to 7.

An assembly consisting of a pair of water-skis is somewhat similar to a small catamaran of which the two hulls would consist of this pair of skis, the skiers feet and legs providing the hull assembling structure and the skiers body acting as the sail support which, in this case, is controlled completely by hand.

The use of a sail by a man in equilibrium on a pair of skis might appear, at first sight, as almost impossible. In fact, it is not only possible, but becomes even very easy provided that the above explained principles of directing sails are applied. Experience teaches that a skilled skier can control a sail of a size of 65 to 100 square feet by relatively strong winds involving a relatively rough sea preventing the practice of conventional waterskiing (i.e., with the skier pulled by a racer or outboard-motorboat).

Preferably, the sail consists of transparent fabric or plastic material, to preserve the skiers visibility ahead. This sail has the shape of a triangle or an isosceles trapezoid, with the two non parallel sides mounted in lightweight spars AB, AC, preferably of aluminium.

A cross spar MM holds in proper space relationship the aforesaid spars AB and AC and stretches the sail. It is so disposed that the sail is balanced at its middle point D, the thrust center CP lying somewhat at the rear, in the surface BMM'C. This spar MM may consist of a rigid spar but consists preferably of a pair of elements pivotably interconnected at D by means of a hinge or like device, so that it can be folded only in the plane of the sail and towards the trailing edge BC, so as to close the sail in the fashion of compasses. Means are provided for locking the sail in its open and stretched position during the actual use of the sail.

Three sheets, each secured to one apex A, B, C, of the sail, converge to a point B. These sheets, when stretched, form a triangular pyramid having a height ED. The length of these sheets is adjustable for regulating the distance ED according to the skiers stature and enabling him to select for his arms a relative spacing consistent with the exertion of the maximum physical strength without impairing his movements. In fact, during the use of the sail of this invention by a water-skier, the latter must hold the sail with one hand at the central area D of the cross spar, and, with the other hand, at the common junction point E of the sheets, thus affording a convenient control of the sail position for sailing in the desired direction. If desired, a rigid boom R may be used to space the point of convergence of the sheets from the central point of the transverse spar.

Firstly, the sail may be shifted in any desired direction, with respect to the vertical. This adjustment of the angle [3 enables the water-skier, by changing the angle formed between his body (the vertical) and the sail, to dose his efforts as a function of the wind force. Moreover, this enables the skier to hover. more or less, as a consequence of the lift produced by properly holding the sail.

Then, the sail may also be shifted in order to change the course followed by the'skier, so as to alter the position of the thrust center in relation to the center of gravity. It is only necessary, therefore, to shift the sail forwards or backwards, or laterally to the right or to the left, or angularly. With these various orientations, a resultant of forces is obtained which directs the skier in the selected direction, as a function of the wind direction to the center of rotation of the skis.

Finally, the orientation of the sails may be modified for tacking with headwind. To do this, the skier must rotate the sail towards the wind and, at the same time, shift the sail from one to the other board. To perform these operations, the skier moves the sail above his head in the feathered position in the winds eye.

Veering with leading wind is particularly easy with V the sail of this invention. The skier has just to shift the sail forwards and to lean his body backwards, so that he will be brought to a leading-wind position. During this movement, the front angle A of the sail has moved downwards while rotating, and the free edge BC of the sail is directed upwards, until it lies horizontally above the skiers head. At this time, the skier must move his body towards the front end of his skis and the sail backwards, so that he can catch the wind from the other side.

These manoeuvres have been described with reference to the general diagram of FIG. 5, but it will readily appear to those conversant with the art that they can be performed with greater ease with a lighter and less cumbersome sail.

In the preferred form of embodiment illustrated in FIG. 6, the sail has a half-elliptic configuration. This sail is stretched on a pair of fiberglass rods having a gradually increasing flexibility, as in the case of angling rods. These rods are secured together, at their upper ends A, by means of a flexible or hinged joint device, and kept at the proper relative spacing by the cross spar MM. The sail of transparent plastic material is secured to the rods at points B and C, and can slide along these rods. The upper end of the sail is secured to a pair of plastic slides G and G interconnected by a cable I-I. This assembly provides a flat sail, when the latter is stretched on curved rods. When closing the sail, by partially folding the cross spar MM, as shown in FIG. 7, the rods are allowed to straighten themselves so that the point A moves to A, and the sail, which cannot be elongated, will slide along these rods with the slides GG. Thus, the following operation is completed, and the sail is easily wound on the rods.

The front sheet is not secured directly to the point A, but passes over a pulley L for engaging the hinge D of the cross spar. Thus, when the sail is folded, the opposite movements of points D and A causes the three sheets to be stretched and become aligned with the rods, so that they can easily be wrapped in the sail. Conversely, when unfolding the sail, it will only be necessary for the skier to grip the portion D of the cross spar with one hand and the point E of the sheets with the other hand, and then pull D towards E in order to open the sail easily and automatically. The traction exerted by the wind on the front sheet will keep the sail open to complete the locking effect produced by the misalignment of the hinge pins MD and DM' and also by the sail tension.

All the manoeuvres described hereinabove are particularly easy to accomplish, and the user can travel, or rather sail, on his ski by directing them at will.

Of course, this invention should not be constructed as being strictly limited to the specific forms of embodiment given herein by way of example, since many modifications and variations may be brought thereto without departing from the basic principle of the invention. Thus, for instance, the above described sail is applicable to the propelling of vehicles such as sand yachts, vehicles designed for travelling on ice surfaces, etc.

What I claim is:

l. Sail assembly comprising a sail having three apices, two lateral spars inclined to one another and intersecting at one of said apices, to which spars the sail is attached, and a transverse spar spacing said lateral spars, said transverse spar being so positioned relative to said lateral spars that the center of gravity of the assembly lies centrally of said transverse spar and the center of thrust of said assembly coincides with or lies behind the center of gravity, and a plurality of sheets of adjustable length, a sheet being attached to said sail at each of said apices and said sheets being joined at a central point, but being otherwise unconstrained.

2. The sail assembly claimed in claim 1 wherein the sail is symmetrical about a line perpendicular to the transverse spar and passing through its center.

3. The said assembly claimed in claim 1 wherein the lateral spars are aluminum or other light alloy tubes and are maintained in curved configuration by the transverse spar and the sail.

4. The sail assembly claimed in claim 1 wherein said transverse spar is rigid.

5. The said assembly-claimed in claim 1 and comprising a rigid boom between the central point of the transverse spar and the junction of said sheets.

6. The sail assembly claimed in claim 1 and comprising float means supporting said assembly and means connecting said transverse spar to said float means.

7. Sail assembly comprising a semi-elliptical sail, two lateral spars comprising fiberglass rods having upper and lower ends, slides slidably mounted at the upper ends of said lateral spars, said sail being secured to said slides and to the lower ends of said lateral spars, a transverse spar spacing said lateral spars, said transverse spar being so positioned relative to said lateral spars that the center of gravity of the assembly lies centrally of said transverse spar and the center of thrust of said assembly coincides with or lies behind the center of gravity, means connecting said slides with one another, a pulley mounted between the upper endsof said rods, hinge means centrally positioned on the transverse spar, two sheets attached to the lower ends of said lateral spars and a third sheet connected to said hinge means and threaded through said pulley, said sheets being joined at a central point. 

1. Sail assembly comprising a sail having three apices, two lateral spars inclined to one another and intersecting at one of said apices, to which spars the sail is attached, and a transverse spar spacing said lateral spars, said transverse spar being so positioned relative to said lateral spars that the center of gravity of the assembly lies centrally of said transverse spar and the center of thrust of said assembly coincides with or lies behind the center of gravity, and a plurality of sheets of adjustable length, a sheet being attached to said sail at each of said apices and said sheets being joined at a central point, but being otherwise unconstrained.
 2. The sail assembly claimed in claim 1 wherein the sail is symmetrical about a line perpendicular to the transverse spar and passing through its center.
 3. The said assembly claimed in claim 1 wherein the lateral spars are aluminum or other light alloy tubes and are maintained in curved configuration by the transverse spar and the sail.
 4. The sail assembly claimed in claim 1 wherein said transverse spar is rigid.
 5. The said assembly claimed in claim 1 and comprising a rigid boom between the central point of the transverse spar and the junction of said sheets.
 6. The sail assembly claimed in claim 1 and comprising float means supporting said assembly and means connecting said transverse spar to said float means.
 7. Sail assembly comprising a semi-elliptical sail, two lateral spars comprising fiberglass rods having upper and lower ends, slides slidably mounted at the upper ends of said lateral spars, said sail being secured to said slides and to the lower ends of said lateral spars, a transverse spar spacing said lateral spars, said transverse spar being so positioned relative to said lateral spars that the center of gravity of the assembly lies centrally of said transverse spar and the center of thrust of said assembly coincides with or lies behind the center of gravity, means connecting said slides with one another, a pulley mounted between the upper ends of said rods, hinge means centrally positioned on the transverse spar, two sheets attached to the lower ends of said lateral spars and a third sheet connected to said hinge means and threaded through said pulley, said sheets being joined at a central point. 